[strong] Disallow implicit conversions for add

src/runtime.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
@@ skipping 142 matching lines @@
   if (IS_STRING(a)) {
     return %_StringAdd(a, %ToString(b));
   } else if (IS_STRING(b)) {
     return %_StringAdd(%NonStringToString(a), b);
   } else {
     return %NumberAdd(%ToNumber(a), %ToNumber(b));
   }
 }
 
 
+// Strong mode ADD throws if an implicit conversion would be performed
+function ADD_STRONG(x) {
+  if (IS_NUMBER(this) && IS_NUMBER(x)) return %NumberAdd(this, x);
+  if (IS_STRING(this) && IS_STRING(x)) return %_StringAdd(this, x);
+
+  throw %MakeTypeError('strong_implicit_cast');
+}
+
+
 // Left operand (this) is already a string.
 function STRING_ADD_LEFT(y) {
   if (!IS_STRING(y)) {
     if (IS_STRING_WRAPPER(y) && %_IsStringWrapperSafeForDefaultValueOf(y)) {
       y = %_ValueOf(y);
     } else {
       y = IS_NUMBER(y)
           ? %_NumberToString(y)
           : %ToString(%ToPrimitive(y, NO_HINT));
     }
   }
   return %_StringAdd(this, y);
 }
 
 
+// Left operand (this) is already a string.
+function STRING_ADD_LEFT_STRONG(y) {
+  if (IS_STRING(y)) {
+    return %_StringAdd(this, y);
+  }
+  throw %MakeTypeError('strong_implicit_cast');
+}
+
+
 // Right operand (y) is already a string.
 function STRING_ADD_RIGHT(y) {
   var x = this;
   if (!IS_STRING(x)) {
     if (IS_STRING_WRAPPER(x) && %_IsStringWrapperSafeForDefaultValueOf(x)) {
       x = %_ValueOf(x);
     } else {
       x = IS_NUMBER(x)
           ? %_NumberToString(x)
           : %ToString(%ToPrimitive(x, NO_HINT));
     }
   }
   return %_StringAdd(x, y);
 }
 
 
+// Right operand (y) is already a string.
+function STRING_ADD_RIGHT_STRONG(y) {
+  if (IS_STRING(this)) {
+    return %_StringAdd(this, y);
+  }
+  throw %MakeTypeError('strong_implicit_cast');
+}
+
+
 // ECMA-262, section 11.6.2, page 50.
 function SUB(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberSub(x, y);
 }
 
 
-// ECMA-262, section 11.6.2, page 50.
+// Strong mode SUB throws if an implicit conversion would be performed
 function SUB_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberSub(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.5.1, page 48.
 function MUL(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberMul(x, y);
 }
 
 
-// ECMA-262, section 11.5.1, page 48.
+// Strong mode MUL throws if an implicit conversion would be performed
 function MUL_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberMul(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.5.2, page 49.
 function DIV(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberDiv(x, y);
 }
 
 
-// ECMA-262, section 11.5.2, page 49.
+// Strong mode DIV throws if an implicit conversion would be performed
 function DIV_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberDiv(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.5.3, page 49.
 function MOD(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberMod(x, y);
 }
 
 
-// ECMA-262, section 11.5.3, page 49.
+// Strong mode MOD throws if an implicit conversion would be performed
 function MOD_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberMod(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 /* -------------------------------------------
    - - -   B i t   o p e r a t i o n s   - - -
    -------------------------------------------
 */
 
 // ECMA-262, section 11.10, page 57.
 function BIT_OR(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberOr(x, y);
 }
 
 
-//ECMA-262, section 11.10, page 57.
+// Strong mode BIT_OR throws if an implicit conversion would be performed
 function BIT_OR_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberOr(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.10, page 57.
 function BIT_AND(y) {
@@ skipping 10 matching lines @@
     if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
     // Optimize for the case where we end up AND'ing a value
     // that doesn't convert to a number. This is common in
     // certain benchmarks.
     if (NUMBER_IS_NAN(x)) return 0;
   }
   return %NumberAnd(x, y);
 }
 
 
-//ECMA-262, section 11.10, page 57.
+// Strong mode BIT_AND throws if an implicit conversion would be performed
 function BIT_AND_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberAnd(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.10, page 57.
 function BIT_XOR(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberXor(x, y);
 }
 
 
-//ECMA-262, section 11.10, page 57.
+// Strong mode BIT_XOR throws if an implicit conversion would be performed
 function BIT_XOR_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberXor(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.7.1, page 51.
 function SHL(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberShl(x, y);
 }
 
 
-//ECMA-262, section 11.7.1, page 51.
+// Strong mode SHL throws if an implicit conversion would be performed
 function SHL_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberShl(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.7.2, page 51.
 function SAR(y) {
@@ skipping 10 matching lines @@
     if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
     // Optimize for the case where we end up shifting a value
     // that doesn't convert to a number. This is common in
     // certain benchmarks.
     if (NUMBER_IS_NAN(x)) return 0;
   }
   return %NumberSar(x, y);
 }
 
 
-//ECMA-262, section 11.7.2, page 51.
+// Strong mode SAR throws if an implicit conversion would be performed
 function SAR_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberSar(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 // ECMA-262, section 11.7.3, page 52.
 function SHR(y) {
   var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this);
   if (!IS_NUMBER(y)) y = %NonNumberToNumber(y);
   return %NumberShr(x, y);
 }
 
 
-//ECMA-262, section 11.7.3, page 52.
+// Strong mode SHR throws if an implicit conversion would be performed
 function SHR_STRONG(y) {
   if (IS_NUMBER(this) && IS_NUMBER(y)) {
     return %NumberShr(this, y);
   }
   throw %MakeTypeError('strong_implicit_cast');
 }
 
 
 /* -----------------------------
    - - -   H e l p e r s   - - -
@@ skipping 467 matching lines @@
 
 /* -----------------------------------------------
    - - -   J a v a S c r i p t   S t u b s   - - -
    -----------------------------------------------
 */
 
 function STRING_LENGTH_STUB(name) {
   var receiver = this;  // implicit first parameter
   return %_StringGetLength(%_JSValueGetValue(receiver));
 }